Electrical measuring instrument.



Patented Apr. 29, I902.

} T. DUNCAN ELECTRICAL MEASURING INSTRUMENT.

(Application filed Mar. 8, 1900.) (No Model.) 2 Sheets-'Sheet I.

Wxtnesses & :EY E5 Patented Apr. 29,1902.

T. DUNCAN. ELECTRICAL MEASURING INSTRUMENT.

(Application filed Mar. 8, 1900.)

2 Sheets-Sheet 2.

(No Model.)

UNITED STATES ATENT OFFICE;

THOMAS DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENSJda HALSKEELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

ELECTRICAL MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 698,690, dated April29,1902.

' A plication filed March 8,1900. Serial No. 7,804. (No model.)

To [tZZ whom it may concern.-

Be it known that I, THOMAS DUNCAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Electrical MeasuringInstruments, (Case No. 360,) of which the following is a full, clear,concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to electrical measuring instruments, and has forits object the construction of an improved form of meter in which ironmay be used electromagnetically where it was hitherto objectionable,because of hysteresis and retentivity.

In practicing my invention the cores are composed of comminutedmagnetizable material, preferably iron-filings, which are held in placeby casings formed of material affording high resistance toedd'y-curr'ents-as, for example, sheet German silver. Sheet-rubber mayalso be employed efficaciously for this purpose.

The invention is of particular utility in connection with commutatedmotor-meters, as cores of iron filings may be advanta geously employedfor the windings thereof. It has heretofore been endeavored to providethe armature and field windings of cominu tated meters with laminated.cores, which have proven unsuccessful, because of hysteresis in theiron. The meters thus constructed would give readings for a given valueuponan increasing load differing from readings upon a decreasing load,due mainly to this cause, tests at difierent watt intervals showing thatthe readings upon a decreasing load are higher than upon an increasingload for the same wattage. For this reason the use of iron as hithertoemployed is objectionable in meters for measuring direct currents.'Butfor these objectionable features in iron as hitherto employed inconnection with direct-current meters its employment would renderdirect-currentmeters very efficient. By employing comminuted orfinely-divided iron I am enabled to overcome these objections and toincrease the efficiency of the meter to an ated by the armature shaft orspindle.

'in a finely-divided state, the changes in magnetism being practicallyinstantaneous.

I.will explain my invention more particularly by reference to theaccompanying drawings, illustrating the preferred embodiment thereof, inwhich Figure l is a front elevation of structural parts of a meter madein accordance with my invention, a system of electrical distributionwith which the meter is associated being dia grammatically indicated.Fig. 2 is a detail View showing an armature suited for a core ofcomminuted magnetizable material and a current field winding having anair-core. Fig. 3 is a plan view showing the core of the armature and amodified form of field-core, the core of the field being shown insection to reveal the filling of comminuted magnetizable material. Fig.4 is a sectional elevation of the preferred form of armature-core andeasing therefor. Fig. 5 is a sectional plan View of one of thefield-cores shown in Fig. 1.

Like parts are indicated by similar characters of reference throughoutthe different figures.

. I have indicated a well-known type of direct-current watfmeter in Fig.1, comprising an armature having coils of even wire 0., constituting thepressure-winding, provided with a collecting device or commutator 1),against which brushes 0 0 rest to include the armature-Winding in bridgebetween the distributing-mains d d, receiving current from adirectcurrent generator (2. The armature and commutator are mounted on aspindle f, at the lower end of which a damping-disk g is secured, whichrotates between the poles of the permanent damping-magnets. Thedistributing mains or conductors d 01 extend to translating devices, oneof the said conductors including a series or current winding, in thisinstance divided into two coils h h. The counting-train or measuringdevice 2' is actu- The armature and field windings of the structureshown in Fig. lare preferably each provided with a com minuted core ofmagnetizable material.

In Fig. 2 I have illustrated a modification, in that the series windingthere disclosed is unprovided with a com minuted magnetizable core.

In Fig. 3 I have illustrated a form of fieldcore in which the cores forthe field-coils are united by a yoke also preferably filled withcomminuted magnetizable material.

The com minuted cores for the armature and field windings are containedin vessels or receptacles that are preferably sealed and which arepreferably made of high-resistance sheet metal, as solder may be used tounite component parts of the receptacles and hermetically seal the same.Sheet German silver is the material preferably employed to form thereceptacles of, although I do not wish to be limited to this material.The casing for the comminuted core of the armature is preferablyconstructed as illustrated in Figs. 3 and 4.. One part 111. of thecasing is in the form of a dish having its rim of reduced diameter toengage a corresponding inverted cap 71, solder being applied at themeeting edge of the cap it with the dish on. A hub 0, preferably made ofbrass, is placed between the parts on and n, the hub being provided withreduced extensions projecting through central'holes in the said parts,the hub o being soldered to the parts m and a. After the parts m and nhave been secured together the com minuted magnetizable material ispoured through the hole 1), filling the space inclosedby the said parts,after which the said hole is sealed in any suitable manner,thegranulated or comminuted iron being thereby hermetically sealed. Thearmature-wire is then disposed about the core thus formed.

The shapes of the cores herein disclosed may be modified withoutdeparting from the spirit of my invention.

The meter illustrated is shown of larger size than is absolutelynecessary, as I am enabled by means of my invention to construct a meterof about one-fourth the usual size of meters. I am thus enabled toconstruct a meter that uses much less current than meters as at presentconstructed.

2. In a system of distribution, the combination with a source of directcurrent, of a wattmeter having current and pressure windings receivingcurrent from said source, and a core of comminuted magnetizable materialfor the pressure-Winding, substantially as described.

3. In a system of distribution, the combination with a source of directcurrent, of a wattmeter having current and pressure windings receivingcurrent from said source, and a core ofcomminuted magnetizable materialfor each of said windings, substantially as described.

4-. In an electricmeter, the combination with the movable windingthereof, of a comminuted core of magnetizable material for said Winding,and means for determining the measurement of the meter, substantially asdescribed.

5. In an electric meter, the combination with current and pressurewindings, the pressure-winding constituting the armature-winding of themeter of a commutator for conveying the current to the pressure-winding,a core of comminuted magnetizable material for said armature-winding,and means for determining the measurement of the meter, substantially asdescribed.

6. In an electric meter, the combination with current and pressurewindings, the pressure-winding constituting the armature-winding of themeter of a commutator for conveying the current to the pressure-winding,a core of comminuted magnetizable material for the current-winding, andmeans for determining the measurement of the meter, substantially asdescribed.

7. In an electric meter, the combination with current and pressurewindings, the pressure-windingconstituting the armature-winding of themeter of a commutator for conveyin g the current to thepressure-winding, a core of comminuted magnetizable material for each ofsaid windings, and means for determining the measurement of the meter,substantially as described.

S. In a wattmeter, the combination with current and pressure windings,of a comminuted magnetizable core for the currentwinding, substantiallyas described.

9. In a wattmeter, the combination with current and pressure windings,of a comminuted magnetizable core'for the pressurewinding, substantiallyas described.

10. In a wattmeter, the combination with current and pressure windings,of a comminuted core of magnetizable material for each of said windings,substantially as described.

In witness whereof I hereunto subscribe my name this 3d day of March, A.D. 1900.

THOMAS DUNCAN.

Witnesses:

MAX W. ZABEL, CHARLES E. I-IUBERT.

